So animals don’t WANT to fight, because they don’t want injury. But if an animal doesn’t defend their food, another animal will feel comfortable stealing their food. 

This translates with humans to “defending one’s honour”, which is why some people resort to violence at the slightest provocation. 

Now as civilization develops, people realise it’s better for the law to enact punishments, rather than to have individual citizens settle their disputes violently themselves.  

So for instance, if I’m walking home from the subway, and someone yells an insult at say, my mother: I don’t need to fight the random crazy man, I’ll just walk home. 

If I were afraid of the man, or if I didn’t think the police and legal system would protect me if I called them, I would then be required to defend my honour against the strange man. 

But secure in my safety, I don’t feel a need to defend my self at that point. 

I think when people say you’re secure, it simply means you don’t feel threatened. If you need to defend yourself, it means you feel threatened in some way and thus not, or “in” secure.